The Galactic CushionThe Hubble Space Telescope recently beamed back pictures of 29 dwarf galaxies in the Perseus Cluster that, by all appearances, should have been torn to shreds by the gravitational tidal forces of their giant neighbors. Instead, like islands of calm in a stormy sea, the little galaxies remain stable and intact. A team of European astronomers says the secret to their cohesion is a cushion of dark matter that protects them from the gravitational tug-of-war outside. Dark matter, believed to be particularly abundant in dwarf galaxies like these, counteracts the pull of the nearby giants, leaving the smaller galaxies in peace.
Hubble’s findings mark the next step in a major research effort aimed at understanding some of the strangest stuff in the cosmos. Dark matter neither emits nor reflects light and cannot be observed directly, posing a challenge for scientists. Although dark matter is thought to be five times as abundant as “normal” matter, finding enough to study has proven difficult.
